Isolation and characterization of a glycosylation mutant from Schizosaccharomyces pombe

N-Linked oligosaccharides were elongated by glycosylation with mannose and galactose residues in the secretory pathway of Schizosaccharomyces pombe, The wild-type S, pombe cells were agglutinated by the additions of not only concanavalin A lectin, which is specific for mannose residues, but also PNA (from Arachis hypogaea) anti RCA (Ricinus communis) lectins, which are specific for terminal galactose residues, By PNA-binding selection, ive isolated an S, pombe mutant defective in protein glycosylation. Thf mutant cells, named gms1, were not agglutinated by PNA or RC:A, In contrast, agglutination of the gms1 sells by the addition of concanavalin A tvas markedly increased, Structural studies on N-linked oligosaccharides from gms1 mutant cells showed that the number of alpha-1,2-linked galactose residues wes markedly reduced and unsubstituted alpha-1,6-linked polymannose outer chains were attached to the sore oligosaccharides.